refactor: add timeout for race condition in heart test (#5131)

* refactor: add timeout for race condition in heart test

* fixup!: set mtime to 0 and check for update

* fixup!: use utimes directly instead of file open

* fixup!: remove import

test/unit/node/heart.test.ts

 import { logger } from "@coder/logger"
-import { readFile, writeFile, stat } from "fs/promises"
+import { readFile, writeFile, stat, utimes } from "fs/promises"
 import { Heart, heartbeatTimer } from "../../../src/node/heart"
 import { clean, mockLogger, tmpdir } from "../../utils/helpers"
 
@@ -33,17 +33,26 @@ describe("Heart", () => {
     const pathToFile = `${testDir}/file.txt`
     await writeFile(pathToFile, text)
     const fileContents = await readFile(pathToFile, { encoding: "utf8" })
-    const fileStatusBeforeEdit = await stat(pathToFile)
+    // Explicitly set the modified time to 0 so that we can check
+    // that the file was indeed modified after calling heart.beat().
+    // This works around any potential race conditions.
+    // Docs: https://nodejs.org/api/fs.html#fspromisesutimespath-atime-mtime
+    await utimes(pathToFile, 0, 0)
+
     expect(fileContents).toBe(text)
 
     heart = new Heart(pathToFile, mockIsActive(true))
     heart.beat()
+    // HACK@jsjoeio - beat has some async logic but is not an async method
+    // Therefore, we have to create an artificial wait in order to make sure
+    // all async code has completed before asserting
+    await new Promise((r) => setTimeout(r, 100))
     // Check that the heart wrote to the heartbeatFilePath and overwrote our text
     const fileContentsAfterBeat = await readFile(pathToFile, { encoding: "utf8" })
     expect(fileContentsAfterBeat).not.toBe(text)
     // Make sure the modified timestamp was updated.
     const fileStatusAfterEdit = await stat(pathToFile)
-    expect(fileStatusAfterEdit.mtimeMs).toBeGreaterThan(fileStatusBeforeEdit.mtimeMs)
+    expect(fileStatusAfterEdit.mtimeMs).toBeGreaterThan(0)
   })
   it("should log a warning when given an invalid file path", async () => {
     heart = new Heart(`fakeDir/fake.txt`, mockIsActive(false))
@@ -52,7 +61,6 @@ describe("Heart", () => {
     // Therefore, we have to create an artificial wait in order to make sure
     // all async code has completed before asserting
     await new Promise((r) => setTimeout(r, 100))
-    // expect(logger.trace).toHaveBeenCalled()
     expect(logger.warn).toHaveBeenCalled()
   })
   it("should be active after calling beat", () => {